Financial Derivative Instruments - Fair Values by Balance Sheet Location (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Gross amounts of recognized assets	$ 1,322	$ 696
Gross amounts of recognized liabilities	47	4
Fuel derivative contracts \| Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Gross amounts of recognized assets	849	409
Gross amounts of recognized liabilities	456	80
Gross amounts offset in the Balance Sheet	456	80
Gross amounts offset in the Balance Sheet	456	80
Fuel derivative contracts \| Other assets
Derivatives, Fair Value [Line Items]
Gross amounts of recognized assets	470	287
Gross amounts of recognized liabilities	150	95
Gross amounts offset in the Balance Sheet	150	95
Cash collateral deposits held from counterparties for fuel contracts - current	150	95
Gross amounts offset in the Balance Sheet	150	95
Fuel derivative contracts \| Other Current Assets
Derivatives, Fair Value [Line Items]
Cash collateral deposits held from counterparties for fuel contracts - current	410	80
Fuel derivative contracts \| Accounts and other receivables
Derivatives, Fair Value [Line Items]
Receivable from third parties for fuel contracts	111	8
Interest rate derivative contracts \| Other assets
Derivatives, Fair Value [Line Items]
Gross amounts of recognized assets	3	0
Gross amounts offset in the Balance Sheet	0	0
Interest rate derivative contracts \| Other noncurrent liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of recognized liabilities	1	4
Gross amounts offset in the Balance Sheet	0	0
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Gross amounts of recognized assets	1,322	696
Gross amounts of recognized liabilities	1	4
Designated as Hedging Instrument \| Fuel derivative contracts \| Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Gross amounts of recognized assets	849	409
Designated as Hedging Instrument \| Fuel derivative contracts \| Other assets
Derivatives, Fair Value [Line Items]
Gross amounts of recognized assets	470	287
Designated as Hedging Instrument \| Interest rate derivative contracts \| Other assets
Derivatives, Fair Value [Line Items]
Gross amounts of recognized assets	3
Designated as Hedging Instrument \| Interest rate derivative contracts \| Other noncurrent liabilities
Derivatives, Fair Value [Line Items]
Gross amounts of recognized liabilities	$ 1	4
Not Designated as Hedging Instrument \| Fuel derivative contracts \| Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Gross amounts of recognized liabilities		$ 46

Derivative, Cash Receivable (Payable) On Hedge

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- Definition

Amount of obligation to return cash collateral under master netting arrangements offset against derivative assets.

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Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Fair value of asset associated with financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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